Lower temperatures reduce stripe rust worries

The cold December weather has reduced the amount of stripe rust in Pacific Northwest wheat fields, experts say.

The new year may start out with relatively low levels of stripe rust in Pacific Northwest wheat fields, two experts say.

Xianming Chen, USDA Agricultural Research Service research geneticist in Pullman, Wash., is forecasting that wheat varieties susceptible to stripe rust will have 22 percent yield loss — the lowest level predicted since 2009.

The reason, he said, is the cold winter.

“We had very cold weather in the first week of December,” Chen said. “That cold weather should reduce the infection that occurred in the fall.”

In his report, Chen said stripe rust was found in November on volunteer wheat plants near Connell, Wash., and in a field of the variety Eltan near Coulee City, Wash., that was planted in July.

If conditions hold from now until the crop matures, Chen said his forecast will be accurate. Rust could spread into the area from other regions, but when that happens, the rust also gets a late start, he said.

If the weather warms up during the growing season, the rust level could increase. When rust starts to develop, the weather could make a difference, Chen said, especially if it is warm in April and wetter and cooler in late May and June.

“We will have rust,” Chen said. “It’s just a matter of how much.”

Stripe rust is typically a mid- to late-season disease, said Mike Flowers, extension cereals specialist at Oregon State University.

“(We) tend to have real bad problems with it when it comes in early,” he said. “The cold temperature and people switching to resistant varieties hopefully will knock down the pressure.”

Flowers said farmers are planting more resistant wheat varieties as they become available.

He recommends farmers walk their fields as temperatures start to increase and plants emerge. The earlier a problem can be addressed, the better, he said.

“If they have a susceptible variety, make sure they’re looking for stripe rust or other diseases,” he said.

Oregon State University researchers have identified a version of septoria that is resistant to fungicide classes available in the Willamette Valley, he said.